.UMAP File Extension

A UMAP file is an Unreal Engine map created for games developed with the Unreal Engine, a free gaming engine used todevelop games such as BioShock, Mass Effect, and Unreal Tournament 3. It contains references to map properties that are stored in the .UPK Unreal Package such as objects, light brightness and direction, fog density and color, and shadow colors.

You can open the UMAP file with UnrealEd (Unreal Editor) and select File → Open Level then choose your UMAP file. If it will not import the file you may have to manually move it to the "Content" folder in your project directory.